Duane, that's an excellent point. But there are a whole bunch of human decisions that put companies behind the eight ball. Management execs aren't going to turn down huge business from Apple or IBM if it throws their model over into an 80/20 situation.
On the other hand, how many companies are there like ADI which I boasts its largest customer is 5 % of the business?
Tough calls... and I'd hate to be in their shoes!

Apple is not vertically integrated because it chooses not to be. It's a business decision. The US government really has very little role in this strategic decision. US based Micron/Intel fabs produce NAND flash chips and we do have NAND flash being manufactured in the US.

I think that shortages of NAND flash are almost guaranteed later this year unless the entire world economy goes into recession. It's time for NAND producers to make a little money for a change. Another fast growing source of demand for NAND chips is the solid state drive market.

Apple goes to TSMC. Samsung says "Oh no you didn't!. Girl! find yo flash 'some place else!"
That would be too simplistic. Samsung and Apple have been very successful partners and not-withstanding lawsuits around curved edges and I doubt they would jeopardize their existing business. Apple most likely has contractual guarantees on flash supplies from Samsung.

As a UK citizen and resident I look across the water at the USA, and am always impressed by its ability to invent and innovate to bring useful and world changing products to the market. Apple epitomizes this aspect of the USA's can do attitude.
I am disappointed that the USA has allowed a situation to develop where a major player such as Apple is forced to hunt-the-marketplace to feed itself. When you're in the jungle you're also on the menu, no matter what size you are.
There is a clear advantage, at a cost, in vertical-integration. I think that the USA needs to address the question 'Why can't and we do it here, and why are we not doing it here?'. This is question for both the US Administration and its industry. After all the health of the USA is inextricably linked to the health of its industry. If the USA is proud of Apple and likes the taste, then plant an orchard and grow some more because the future is out-there.
It is very much like when someone says
'but education is so expensive'. My answer is 'If you think education is expensive try ignorance'.
There is a quote to which I often refer,'it is better to strike a candle than curse the dark'.
Ron Boyce.

Micron makes about one seventh of the NAND flash market by value.
I am sure they would be eager to supply Apple.
My point is that ALL five NAND flash makers have made efforts not to over-invest in production capacity over the last five years. As such it is possible that in 2013 NAND flash memory could be undersupplied.
Shortages of memory will drive prices up and could even introduce the dreaded A word....allocation.